[Micah]

The rulebook actually states that the drn for global overwrites is a single die, not two. No idea if it actually IS one die or not, but there's at least some reason to suspect that it may be different from the other random die rolls in the game. Aside from that vfb nailed everything in his post. (And if someone has tested it to be with 2 dice please speak up about that specifically, I haven't heard anyone mention it before now as being a departure from the rulebook, but as we know there are quite a few inaccuracies in the book.)